;(function(window,undefined) {
  function init(el){
    let els=document.querySelectorAll(el)
    for (let i=0;i<els.length;i++){
      this[i]=els[i]
    }
    this.length=els.length
  }
  let jQuery=function(el){
    return new init(el)
  }
  jQuery.extend=function(object){
    for(let key in object){
      init.prototype[key]=object[key]
    }
  }
  init.prototype={
    css(cssAttr,cssVal){
      for (let i=0;i<this.length;i++){
        this[i].style[cssAttr]=cssVal
      }
      return this
    }
  }
  window.jQuery=window.$=jQuery
})(window)